There can be a couple of issues, one of which is a corrupted Office installation. Are you seeing the Invalid source specified in
the document or also in the Manage Sources=>Edit sample at the bottom of the dialog?
With Word closed, if you use Start=>Search and rename the file Sources.xml temporarily and start Word and create a new source do you
still get the same issue?
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Bob Buckland ?
MS Office System Products MVP
*Courtesy is not expensive and can pay big dividends*